Cualidades físicas básicas involucradas en el lanzamiento de peso y martillo

A conceptual framework to understand dynamics of regional sectorial water use

Globally, the growing water use is approaching the total renewable fresh water availability (Wiek and Larson 2012). Even for the water abundant Pearl River Basin, water resource is scarce during the dry season. Sustainable water resource management requires both water resource and water use to be managed more efficiently and effectively (Gleeson et al. 2012). To assess the sustainability of sectorial water use in large countries like China, understanding the water use behaviour of water users at the regional level, as well as on the monthly scale, is crucial. This is where my study started to contribute.

On a small scale, like a household, or in a community, or for a specific production sector, many advanced complex models exist to accurately simulate the water use

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Therefore, my study started from a simple conceptualization of water use based on well recognized equations from global water use models (Chapter 2), and presented the first consistent and comprehensive assessment of water use in the most densely urbanized delta region in the world, the Pearl River Delta. Firstly, this conceptualization of water use provides a method to homogenize the poorly reported, scattered information and reveals the trends of sectorial water use on regional level. Secondly, it offers the advantage to explore insights of driving forces behind the trend by linking the water use with corresponding socio-economic development indicators.

My study showed that the parameters used in the global assessments need to be regionalized based on regional historical records. Well recorded sectorial water use data and corresponding socio-economic data on regional scale, and even better, on (sub-)sectorial level, are crucially important in calibrating the regional specified parameters. Otherwise the estimation may over- or under-estimate the sectorial water uses on regional scale.

To reveal the underlying causes behind the reported water shortages in the PRD, understanding of the monthly fluctuation in water use and availability is required, due to the highly uneven temporal distribution of water resource in the region. Assessing future water scarcity in the Pearl River Basin, as well as developing sustainable management strategy, also requires obtaining better understanding of monthly dynamic of sectorial water uses. This is consistent with the recent global assessment that reports that for an assessment at monthly resolution, the population suffering water scarcity increases by more than 40% compared to an assessment using only annual data (Wada et al. 2011).

Thus, I further elaborated the conceptualization of water use to the monthly scale (Chapter 3). By obtaining insights of monthly fluctuation of water use and availability, I find that the off-stream water use further deteriorates the salt suppressing capacity of the runoff, thus contributes to the salt intrusion. This shows how freshwater shortages in a complex delta region result from the interplay of dynamic processes could easily be attributed to “natural” phenomenon, thereby overlooking the contribution of human activities.

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The ability to analyse the monthly water balance further allowed me to evaluate different coping strategies for solving the severe salt intrusion (Chapter 3), and development strategies (Chapter 5).

Linking scenarios across geographical scales

Together with the uneven distribution of water resources, rapidly increased water use aggravates the water shortage conditions around the globe, and increases the risk of being unable to sustain the future socio-economic growth (Jiang 2009, Taylor et al. 2013, Wada and Bierkens 2014, Wada et al. 2011). Human activities and climate change both alter the dynamic of the hydrological system on multiple scales (Haddeland et al. 2014). Expected future changes on socio-economic development and climate will, on one hand, increase the pressure on available water resources, while on the other hand, compromise the availability of water resources in many regions, as well as globally (Schewe et al. 2014). Sustainable water resource management and planning for future economic development and investigation, requires projection of both the water availability and water use to safeguard sustainable access to freshwater (Harrison et al. 2016, UN-Water 2013, Wada et al. 2016).

The impacts of socio-economic development on sectorial water uses on global scale has been assessed by several studies, including the recent estimation of global sectorial water use using a set of state-of-the-art water scenario based on the Shared Socioeconomic Pathways (SSPs), and the Representative Concentration Pathways (RCPs) (Wada et al. 2016). But there is no study yet investigates whether these global level scenarios and information generated are relevant to help achieve sustainable management goals on regional level.

Thus, I introduced a scientifically sound and feasible method to derive the scenario assumptions for regional assessment of sectorial water use by linking regional specified historical trends and future development targets with the national SSPs scenarios (Chapter 4). The results showed that the method can generate the regional water scenarios that capture the fluctuations in regional sectorial water use dynamics, and at the same time be consistent with global assessment.

The methods developed in this thesis in principle are transferable, and the results are comparable under the same global scenario study framework. However, the Pearl River Delta is rather unique in comparison with other delta areas. Taking the other two large deltas in China as example, the Yangtze Delta and the Yellow River

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129 Delta, the methods of the present thesis can be applied on these two delta regions, but the results would be different.

Yangtze Delta is the most industrialized delta region in China, where the industry sector uses more than 80% of the water for production (Buureau of Hydrology 2011). Domestic and agriculture sectors are therefore less influential in affecting off-stream water use, despite the huge population of the Yangtze River Delta. Yangtze River Delta is also one of the oldest industrialized regions in China. The industrial structure there has been well established and developed for very long time. This implies that the future water use projection for Yangtze River Delta would 1) mostly depends on the industrial water uses, and 2) technological improvement rather than structural changes.

Moreover, difference in socio-economic development between upstream and downstream areas along the Yangtze River Basin is significantly less than of the Pearl River Basin. Competing pressures from upstream area due to future development may be less in the Yangtze River Basin, than in the Pearl River Basin. In case of the Yellow River Basin, both the delta area and upstream basin are under- developed in comparison with the Pearl River Basin and Yangtze River Basin. Agriculture dominates the water use in the whole basin, indicating the large potential to increase, but also to improving the efficiency of industrial and domestic water uses. Moreover, the socio-economic development is relatively homogeneous across the Yellow River Basin. Thus, when applying the presented methodology, one set of basin-specific scenario may be enough for the Yellow River Basin, instead of developing two separate sets of scenarios for the upstream basin and the delta region, respectively.